rs6000.c (rs6000_gimple_fold_builtin): Add support for early gimple folding of vec_splat().

[gcc]

2018-09-06  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add support for
	early gimple folding of vec_splat().
	* tree-vect-generic.c: Remove static from tree_vec_extract() definition.
	* gimple-fold.h: Add an extern define for tree_vec_extract().

From-SVN: r264146

gcc/ChangeLog

 2018-09-06  Will Schmidt  <will_schmidt@vnet.ibm.com>
 
+	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add support for
+	early gimple folding of vec_splat().
+	* tree-vect-generic.c: Remove static from tree_vec_extract() definition.
+	* gimple-fold.h: Add an extern define for tree_vec_extract().
+
+2018-09-06  Will Schmidt  <will_schmidt@vnet.ibm.com>
+
 	* config/rs6000/rs6000.c (fold_mergehl_helper): Add types_compatible_p
 	wrappers around TREE_TYPE comparisons.
 

gcc/config/rs6000/rs6000.c

@@ -15772,6 +15772,48 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
 	 gimple_set_location (g, gimple_location (stmt));
 	 gsi_replace (gsi, g, true);
 	 return true;
+	}
+
+    /* Flavors of vec_splat.  */
+    /* a = vec_splat (b, 0x3) becomes a = { b[3],b[3],b[3],...};  */
+    case ALTIVEC_BUILTIN_VSPLTB:
+    case ALTIVEC_BUILTIN_VSPLTH:
+    case ALTIVEC_BUILTIN_VSPLTW:
+    case VSX_BUILTIN_XXSPLTD_V2DI:
+    case VSX_BUILTIN_XXSPLTD_V2DF:
+      {
+	arg0 = gimple_call_arg (stmt, 0); /* input vector.  */
+	arg1 = gimple_call_arg (stmt, 1); /* index into arg0.  */
+	/* Only fold the vec_splat_*() if arg1 is both a constant value and
+	   is a valid index into the arg0 vector.  */
+	unsigned int n_elts = VECTOR_CST_NELTS (arg0);
+	if (TREE_CODE (arg1) != INTEGER_CST
+	    || TREE_INT_CST_LOW (arg1) > (n_elts -1))
+	  return false;
+	lhs = gimple_call_lhs (stmt);
+	tree lhs_type = TREE_TYPE (lhs);
+	tree arg0_type = TREE_TYPE (arg0);
+	tree splat;
+	if (TREE_CODE (arg0) == VECTOR_CST)
+	  splat = VECTOR_CST_ELT (arg0, TREE_INT_CST_LOW (arg1));
+	else
+	  {
+	    /* Determine (in bits) the length and start location of the
+	       splat value for a call to the tree_vec_extract helper.  */
+	    int splat_elem_size = TREE_INT_CST_LOW (size_in_bytes (arg0_type))
+				  * BITS_PER_UNIT / n_elts;
+	    int splat_start_bit = TREE_INT_CST_LOW (arg1) * splat_elem_size;
+	    tree len = build_int_cst (bitsizetype, splat_elem_size);
+	    tree start = build_int_cst (bitsizetype, splat_start_bit);
+	    splat = tree_vec_extract (gsi, TREE_TYPE (lhs_type), arg0,
+				      len, start);
+	  }
+	/* And finally, build the new vector.  */
+	tree splat_tree = build_vector_from_val (lhs_type, splat);
+	g = gimple_build_assign (lhs, splat_tree);
+	gimple_set_location (g, gimple_location (stmt));
+	gsi_replace (gsi, g, true);
+	return true;
       }
 
     /* vec_mergel (integrals).  */

gcc/gimple-fold.h

@@ -61,6 +61,7 @@ extern bool gimple_fold_builtin_snprintf (gimple_stmt_iterator *);
 extern bool arith_code_with_undefined_signed_overflow (tree_code);
 extern gimple_seq rewrite_to_defined_overflow (gimple *);
 extern void replace_call_with_value (gimple_stmt_iterator *, tree);
+extern tree tree_vec_extract (gimple_stmt_iterator *, tree, tree, tree, tree);
 
 /* gimple_build, functionally matching fold_buildN, outputs stmts
    int the provided sequence, matching and simplifying them on-the-fly.

gcc/tree-vect-generic.c

@@ -120,7 +120,7 @@ typedef tree (*elem_op_func) (gimple_stmt_iterator *,
 			      tree, tree, tree, tree, tree, enum tree_code,
 			      tree);
 
-static inline tree
+tree
 tree_vec_extract (gimple_stmt_iterator *gsi, tree type,
 		  tree t, tree bitsize, tree bitpos)
 {